The aggregation of sickle cell hemoglobin (HbS) is being studied by means of photon correlation spectroscopy (PCS) using IR radiation, pulsed field gradient nuclear magnetic resonance (PFG-NMR), and by sensitive rheological techniques. The elasticity of the gels is being measured with a Zimm-Carothers elastometer and by light scattering methods developed at NIH by R. Nossal. Basic understanding of the aggregation process is sought.